Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication, obtain sensitive information, or cause a denial of service (disk corruption) via backspace characters in the (1) grub_username_get function in grub-core/normal/auth.c or the (2) grub_password_get function in lib/crypto.c, which trigger an Off-by-two or Out of bounds overwrite memory error. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-8370
